George hand smith



Unrrnn STATES 'ATnNr Fries.

Gnonen HAND sMrrH, or noonns'rnn, new roan.

MANUFACTURE OF WHITE LEAD.

SPECIFICATION forming part of Letters Patent 1103303278, dated August 12, 1884.

Application filed Juno 3, 188-]. (No specimens.)

To (Z1? whom it may concern:

Be it known that I, GEORGE HAND SMITH, of Rochester, in the county of Monroe, in the State of New York, a citizen of the United States of America, temporarily residing at their more effectual combination with the aid of suitable apparatus adapted to facilitate such. chemical action with more rapid production of white lead of a good marketable quality,

like in character to that produced by the wellknown Dutch or Anglo-Dutch process.

The object of the improvements is to obtain as nearly as may be those conditions most favorable to combination of the elements conducive to the production of the white load which exist in the aforesaid Dutch process, while avoiding or dispensing with the employment-of the objectionable and uncertain bark,

spent tan, or other decomposing heap or stack of material employed in that process for generating the moisture, heat, and carbonic acid employed in the reaction. This I cffcctby conducting the improved operation on the lead in a. suitable chamber or vessel. or chambers or vessels in which such lead in the blue or metallic state with the other elements necforated, or formed into sheets with perforations, or other suitable forms, or disintegrated in any suitable manner best adapted to facilitate superficial exposure of the metallic or blue lead to the action of the corrosive agents,

. and this lead I then arrange in layers or series permitting of free circulation of the gaseous and vaporous elements throughout them, so as to favor combination within a chamber or was sel made of non-conducting-matcrials or othcr- Wise so constructed as to prevent radiation or conduction away, and consequent loss of heat, from the same, as far as possible. By constructing this chamber with non-conducting inclosing-casing I am enabled to maintain therein with greater certainty and economy any desired temperature for a prolonged pcriod. Into this chamhcror vessel so constructed, and containing the metallic lead to be treated arranged in suitable layers, I introduce a mixture of air and carbonic-acid gas, in suitable proportions rclatively, for effecting the desired corrosion or decomposition of the lead.

This mixture of air and gas is, before being introduced to the chamber containing the lead, first heated by any convenient means to a suitable temperature, and then passed next through a vessel, which 1 call a saturator also heated by the heating means which heats the operatingchamber, and containing and adapted to give off li qui d to such mixture in the form of vapor; and, finally, this mixture of air and gas, now charged or saturated with aqueous vapor and acetic acid also provided in this chamber when required, is conducted into the operating-chamber to act on the lead therein. The temperature at which this operation may be effected can be varied Within a considerable range; but I have had good results when employing a temperature of from about 120 to 140 Fahrenheit. the acetic acid, diluted with water, may be introduced into the corroding-chambers by means of a tray or other suitable containing vessel. Under these conditions white lead is produced; but I iind in practice that, by first supplying these gases thus saturated at a slight the lead-operating chamber, and then permitting them to expand therein, whereby these gases are more effectually saturated with moisture when within the chamber or vessel. in the presence of the lead, a greatly-increased chemical action is set up, resulting in an increased production of white lead.

I employ any suitable method of production If desired,

' but definite pressure before introduction into of carbonieacid gassuch as by the action of hydrochloric acid upon chalk, or by the combustion of coke, or of a mixture of coke and chalk, and subsequent purification, or other well-known agency may be employed.

The resulting gas or mixture of gases mixed with the proper proportion of air may be stored in a suitable reservoir or gasometer, and then supplied to and caused to pass through a suitable saturator kept at a heat of a desired temperature, so as to cause such gaseous mixture to become saturated or charged with moisture from liquid contained in that saturator, consisting of water orwater and acetic acid.

'Iumps or other suitable forcing means may be employed to cause the flow of the gaseous mixture through the apparatus, and pressure and heat may be given to the said gases in the saturator, and to be maintained until the same is permitted to enter the lead-containing chamber, by means of suitable conduits. The moisture-laden gaseous mixture on entering the operating-chamber becomes released from pressure, inducing a condition of such atmosphere most favorable to the production of the white lead.

One form of saturator which I employ consists of a shallow, oblong, closed box or chamber of copper or other suitable material adapted to resist corrosion, provided with inlet and outlet pipes at opposite ends, or so arranged as to insure the fullest possible saturating action of the moisture from the contained water or water and acetic acid, the dispersion thereof into the passing air and gas being aided by a series of diaphragms or sheets of porous materialsueh as cotton cloth or other suitable substance-adapted to hold suspended the liquid, while offering little resistance to the flow of the gaseous fluid through them in a heated state favorable to such absorption.

Steam may be employed for the saturation of the gases, but care should be taken to prevent the admission into the lead-containing chamber of excessive condensed moisture, to the detriment of satisfactory action. 7

The lead containing chamber I form of metal or other suitable material capable of being heated to and maintained at the same temperature as that of the gases issuing from the saturator, and conveyed to such lead-chamber. Radiation or loss of heat from these chambers where the operation upon the lead, and also those employed for effecting the'saturation, may be prevented; or the heat therein may be efficiently controlled by inclosing those chambers with other surrounding walls, or with in tervening cells or spaces, so that air or gas eous fluid or vapor heated to the desired temperature may be suppliedto and retained in them.

According to another modification, I employ chambers or vessels made'of nonconducting materialssuch as Wood or wood and felt or other heatretaining medium.

The heat for the lead-containing chamber may be obtained by the passage therethrough of heated gases; or this heat may be supplied by means of a water bath deriving its heat in turn from gasjets or other source of heat; or the heat from the passing gases in that chamber may be supplemented by the aid of steampipes or hot-air tubes or other suitable means.

The time of treatment required will necessarily depend upon the thickness or relative surface exposed of a given quantity of lead operated upon, and the strength of the acetic acid solution may also vary somewhat; but I have obtained good results when using acetic acid in the saturator mixed with water in the proportion of seventy five one-hundrcdths per cent. of acetic acid; but when used in the lead-operating chamber, the strength of that solution may be somewhat greater.

The air and the carbonic acid gas employed may be saturated separately with the required vapor and acetic acid, and then allowed to mix in the operating-chamber or corrodingvessel. WVhen preferred, dilute nitric acid may be employed instead of acetic acid; or dilute nitric acid mixed with acetic acid may be so employed.

It will be perceived from the above, that my method of manufacture is under very different conditions from the ordinary methods, as I do not introduce any spray or jets.

I claim The process, substantially as described, of manufacturing white-lead, consisting in submitting metallic or blue lead while in a closed chamber to the corroding action of acid, vapor, and air introduced in regulated quantity and proportions under the conditions of teinature and of outside pressure, as set forth, whereby uniformity in said proportions, temperature, and pressure may, besustained.

In testimony whereof I affix my signature in the presence of two witnesses;

GEORGE II AND SMITH.

Witnesses:

E. MEIGS SMITH, ALFRED DoNNIsoN. 

